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Thread: 81 Range Rover 3.5 4 speed manual. What RPM at 100K is norm?

  1. #1
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    81 Range Rover 3.5 4 speed manual. What RPM at 100K is norm?

    Hello to all.

    I just went out and bought myself my first Rangie, which also happens to be my first 4WD, so please excuse any obvious ignorance.

    I have only had the rangie a few days now so I am just getting used to everything.

    I was wondering what would be considered as a normal RPM range for travelling at 100Kph on a level piece of freeway, for a carby 3.5 with a 4 speed gearbox.

    The rangie has an aftermarket tacho strapped to the dash but I fear it is not too acurate, I haven't had a chance to test witha proper tacho yet.

    I expect the RPM to be around 3000 - 3500 does that sound correct/normal?

    I would like to say hello and that there is a chance I will come up with more questions, although, just like in this case I will be sure to search through the forums to see if it has been covered already first. Which in this case I couldn't find a similar topic...sorry if it has been covered already...

  2. #2
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    welcome to the site mate

    and also welcome to the landy family :wink:


    in regards to your question, i cant help you there 8O

    but hang tight and the forum guru's will tell you shortly


    ps hope all goes well with your rangie

    also pop a location in your profile
    130's rule

  3. #3
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    Thanks for the warm welcome...


    I will update my profile...

  4. #4
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    ha...I just noticed your location hiline...

  5. #5
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    that makes 4 of us now
    130's rule

  6. #6
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    It depends on the year model. the models up to 1980 had a low high range gear in the transfer, I do not remember which and if I recall revved at about 3500- 3600 at 100Kmh.
    1981 had a considerably higher(and quieter) high range gear and revved lower . Again this is many years ago but I think about 3300.

    Regards Philip A

  7. #7
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    OK I knew I was wrong as soon as I posted this.
    Here goes.
    According to a web calculator the high ratios are 1.174 ( I presume up to 80 but it doesn't say)
    and 1.113 ( I assume 81)
    Went to a US rev calculator and input 29.5 inches tyre diameter for a 205x16 and 3.54 for the diff ratio.

    Comes to 2419 RPM X 1.174 = 2839 RPM.
    With the 1.113 is 2692 RPM.

  8. #8
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    Originally posted by PhilipA
    OK I knew I was wrong as soon as I posted this.
    Here goes.
    According to a web calculator the high ratios are 1.174 ( I presume up to 80 but it doesn't say)
    and 1.113 ( I assume 81)
    Went to a US rev calculator and input 29.5 inches tyre diameter for a 205x16 and 3.54 for the diff ratio.

    Comes to 2419 RPM X 1.174 = 2839 RPM.
    With the 1.113 is 2692 RPM.

    My 1976 did 2500rpm @80kph

    Calculate kph/1000rpm using this

    kph/1000rpm =60000/(gear ratio X Transfer X diff X tyre rev/km)

    205R16 = 448rev/km
    750R16 = 409rev/km

    a 1976 RR 4th gear = 1:1
    high range = 1.113:1
    diff = 3.54:1

    which gave 34.0kph/1000rpm for 4th high on 205R16



    Bushie

  9. #9
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    Thanks for the information. Seeming as though I am still learning how everything feels and acts in the rangie I wasn't sure what to expect the engine to rev at 100 kph.

    I thought it may be a little high for a v8 to happily tick over at for long periods of time. But I suppose the fact that there are still so many on the road seems to suggest they will do ths happily.

    When I bought the car, the mechanic sugested that the gearbox was not the original becuase it had a short shift between gates. He suggested the 81 gearbox had a longer shift between gears. So going by this it is quite possible that it is a high ratio box.

    I suppose it leads me to the question of whether a 5 speed box is a better option or not. Reading other post seems to suggest that the 5speed box was pretty weak. If that is the case should I stick with the higher revs at 100 Kph for the sake of having a strong gearbox.

  10. #10
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    Welcome to the site mate - I'm sure there are some guys here that can help.
    2023 Defender 130 D300
    SOLD - 2010 Discovery 4 V8
    SOLD - 2008 Range Rover Vogue L322 TDV8
    SOLD - 2006 Range Rover Sport L320 TDV6
    SOLD - 2002 Range Rover L322 TD6
    SOLD - 2002 Discovery 2 TD5
    SOLD - 1997 Range Rover 4.6 HSE
    SOLD - 1999 Range Rover 4.0 SE

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